Henry Mitchell was an agent in the CIA.He was actually a partner of Hyman Roth for at least a decade,and after Aldo Trapanis succesor,Dominic,started allying himself with Roth,Roth and Mitchell asked Dominic to kill Alejandro Almeida,Almeida Family soldrier,who was starting a strike with the airport workers at Miami,Florida.Mitchell later met Dominic at the Florida docks with Hyman Roth,the two told Dominic that they could fix all his problems if he help them kill Castro in Havana,Cuba to bring back the ex-president.After Dominic failed to kill Castro,Mitchell went rogue and started working for another family,Michael Corleone then told Dominic that Mitchell could become dangerous and ordered to kill him.Dominic and his crew then went to Cuba to kill Mitchell which Dominic did; ending Mitchell's life.